UP NEXT:Diamondbacks vs. DodgersWhen: Wednesday at 6:40 p.m.Where: Chase Field.Roof hotline: 602-462-6262.TV: FSAZ.Radio: 620 AM, 106.9 FM, 710 AM.Pitchers: Diamondbacks LHP Tyler Skaggs (2-1, 3.65) vs. Dodgers LHP Hyun-Jin Ryu (7-3, 2.82).Notable: Skaggs is making his fifth start and is coming off an impressive outing last Friday in which he pitched eight scoreless innings against the Rockies. In his only previous start against the Dodgers in September, he received a no-decision, allowing one earned run over five innings. … Ryu has allowed three runs or more only twice this season and has 14 quality starts. He is 1-0 in two starts against the Diamondbacks in 2013, earning a win in a 7-5 victory at Chase Field on April 13. He has a 1.90 ERA in nine starts at home and a 3.96 ERA in eight starts on the road.

Over the past week, the Diamondbacks’ more dependable starters might have been the three who competed for the No. 5 spot in the rotation during spring training, two of whom opened the year in Triple-A Reno, where they struggled to post ERAs under 7.00 for the first six weeks of the season.

This might sound bizarre, but in actuality it’s just the sort of unpredictability that we’ve come to expect from the world of pitching. Can’t-miss prospects miss. Established pitchers fall off. Less-heralded guys turn into aces.

Consider these five pitchers, all of whom spent time in the Double-A Mobile rotation in 2011: Trevor Bauer, Tyler Skaggs, Jarrod Parker, Wade Miley and Pat Corbin. Baseball America rated those five pitchers in that order after the season in their prospect rankings. How different would those rankings look today?

When right-hander Matt Harvey was nearing the big leagues, Mets officials cautioned not to expect too much from him, and most scouts agreed, pegging him as more of a mid-rotation starter than one with ace potential. But now 28 starts into his career, Harvey rates among the top pitchers in baseball.

Some scouts didn’t even see mid-rotation potential in Corbin, projecting him as a back-end guy or even a lefty reliever. He’ll join Harvey next week in New York for the All-Star Game.

When it comes to developing pitching, this is just the nature of the beast. One study of Baseball America’s annual top prospects lists showed that pitching prospects flop three-quarters of the time. That is to say, the industry rates the top 100 prospects across the game, and three of four pitchers on the list will flame out.

“It’s a little callous to sort of say you try to accumulate as many guys as you can,” one American League executive said. “You don’t want these guys to think they’re just sort of random assets. But there’s a sense now more so than 10 years ago that if someone is performing in the minor leagues you want to sort of reap the benefits of that at the major-league level and you push them to get there. You don’t want to sort of waste bullets in the minor leagues. You assume they’re going to get hurt at some point and because their performance fluctuates so much you try to get guys up while they’re hot.”

And it’s not as if the established ones are a whole lot more predictable. The Diamondbacks entered the season with four starters in their rotation with track records of getting big-league hitters out. Those four — Ian Kennedy, Trevor Cahill, Brandon McCarthy and Miley — had a combined 4.67 ERA this season entering Tuesday.

Look around the league. Where there were once No. 1 or 2 starters, there are now pitchers whose results have drastically declined or they are casualties sitting on the disabled list. There’s Roy Halladay and Matt Cain, David Price and Josh Beckett, Tim Lincecum and Dan Haren, CC Sabathia and Jon Lester.

All have seen fairly precipitous drops in performance either this season or last, and all are making at least $10 million, some earning twice that.

“There are still guys who can be counted on year in and year out, still prospects who turn into Clayton Kershaw,” the executive said. “But still, you don’t really know. A few years ago, Colorado brought up Ubaldo Jimenez and Franklin Morales and they had Jorge De La Rosa. It looked like they were going to have a great staff for a while. A year later, only one of those guys was left standing.”

The San Francisco Giants are getting a taste of this for the first time in a while. Somehow, they were able to maintain a dominant starting rotation for years, one that rated in the top five in the league for five of the past six seasons. This year, Giants starters rank 13th with a 4.60 ERA.

It all makes for a tricky equation for the Diamondbacks as they hurtle toward the trade deadline: Do they hope for high-level production from their prospects, knowing that the odds aren’t necessarily in their favor, or do they deal for someone more established, knowing that even that route is fraught with uncertainty?

Posting a comment to our website allows you to join in on the conversation. Share your story and unique perspective with members of the azcentral.com community.

Comments posted via facebook:

► Join the Discussion

Join the conversation! To comment on azcentral.com, you must be logged into an active personal account on Facebook. You are responsible for your comments and abuse of this privilege will not be tolerated. We reserve the right, without warning or notification, to remove comments and block users judged to violate our Terms of Service and Rules of Engagement. Facebook comments FAQ

Join thousands of azcentral.com fans on Facebook and get the day's most popular and talked-about Valley news, sports, entertainment and more - right in your newsfeed. You'll see what others are saying about the hot topics of the day.